The market for LCD's is increasing rapidly, especially in their applications to notebook PCs and monitors. When LCD panels of larger size and higher resolution are used for desktop monitors, a wide-viewing angle (WVA) and fast response time become very critical in meeting the monitors' requirements. In addition to contrast ratio with respect to different viewing angles, gray-scale inversion, colorimetry, and the optical response of a LCD are important factors of a high quality LCD panels. However, the cost associated with designing and manufacturing a panel also needs to be considered.
Controlling liquid crystal domains is the most important technology in obtaining a wide-viewing angle for a vertically aligned LCD. Most of the conventional LCD's are 90.degree. twisted nematic (TN) LCD's having a LCD panel and crossed polarizers attached outside. The drawbacks of the conventional LCD's include narrow viewing angles (.+-.40.degree. horizontally and .+-.30.degree. vertically), slow response (about 50 ms), and large color dispersion. Therefore, it is difficult to make high quality LCD panels. Also, the rubbing process required in manufacturing the panels causes electric static damage (ESD) and particle pollution.
Because of the demand in high quality LCD panels with a wide-viewing angle, the structure of multi-domain vertically aligned LCDs has been developed. Such LCD panels have compensation films and crossed polarizers outside the liquid crystal display panel. The liquid crystal mode is multi-domain vertically aligned. The LCD panel has a wide-viewing angle and small color dispersion. In addition, it does not have electric static damage and particle pollution problems because no rubbing process is required.
Several different structures for the conventional multi-domain vertically aligned LCD's have been designed. For example, the ridge and fringe field homeotropic aligned (RFFHA) structure of IBM has a Y and inversed-Y shaped bump structure as shown in FIG. 1. The Y and inversed-Y shaped bump structure is formed in the central portion of a pixel electrode. Fujitsu's multi-domain vertically aligned (MVA) structure has W-shaped bump structures as shown FIG. 2. The W-shaped bump structures are formed on both upper and lower substrates. Although the rubbing process has been eliminated in manufacturing these LCD panels, complicated manufacturing steps are required. For example, it is necessary to form bump structures on both upper and lower substrates for Fujitsu's structure.